the major risks in tbm bored tunnels projects

I

CCP Certification Technical Paper

The Major Risks in TBM Bored Tunnels Projects

(May 2016)

Engr. Haytham Baraka,

Civil Engineer, PMP, CCP, PMI-SP, PMI-RMP.

II

Table of Contents Page

List of Tables III

List of Charts IV

List of Equations V

Abstract VI

2. Literature Review 1

2.1 The Construction Of Tunnels By TBM Method 1

2.2 Risk Management and Success Factors 2

2.2.1 Introduction to Risk Management 2

2.2.2 Plan Risk Management 3

2.2.3 Identify Risks 3

2.2.4 Perform Qualitative Risk Analysis 4

2.2.5 Perform Quantitative Risk Analysis 4

2.2.6 Plan Risk Responses 5

2.2.7 Monitor and Control Risks 5

3. A Case Study 6

3.1 Establishing The Context 6

3.2 Risk Identification 8

3.3 Qualitative Risk Analysis 13

4. Conclusion 14

Bibliography 15

III

List of Tables Page

Table 1, “Stakeholder Analysis ” 7

Table 1, “Risks List ” 8

IV

Page ChartsList of

Chart 1, “Risk Categories %” 8

Chart 2, “Risk Ranking” 13

V

Page List of Equations

Equation 1, “Risk Ranking ” 13

VI

Abstract

The goals of risk management are to identify risks and develop strategies to reduce

or avoid negative risks and on the other hand to catch opportunities. The value being

added by risk management becomes very obvious when we deal with a complex

project like tunnels construction. This paper represents an overall view on identifying

risks and qualitative assessment regarding a real tunneling projects. There are a

number of methods to construct a tunnel, but this paper will focus on TBM method

which is a common tunneling method.

Key words: Risk management; Construction; Tunnels; Identifying risks; Qualitative

assessment.

Audience:

Project managers: because it represents an overall view to risk

management.

Project staff: because it supports them to identify, monitor and control

risks.

Suppliers and contractors: because it supports them to obtain a

better planning and better outcomes for sellers as well as buyers.

Financiers: because it supports them to obtain a financial reward

commensurate with the risks involved.

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1. Introduction

Construction industry is a key economic activity in any country and contributes to all growth

plans. The success of construction sector has a high effect on all sectors because of the strong

relation in-between these sectors. This relation in addition to the internal circumstances of

construction industry are a primary reason of many challenge that must be managed well to

finally have not only a successful project but also a good economy.

Any project has a big number of probable events which are resulted from uncertainties, so if you

don`t control the way of these events, it will control the way of your project and it will become

out of control. The goal of risk management is to manage the uncertainty and drive your project

forward to the targeted destination. Risk management aims to identify risks, develop strategies

to reduce or avoid negative risks, and on the other hand to catch opportunities. Risk

management supports project stakeholders to make informed decisions to achieve the project

objective. It must be applied to all projects in different degrees according to importance of the

project.

There are some different methods for tunneling, but generally they are risky projects. Tunnels

projects are usually very complicated because the complex technique of construction, rough

circumstances, high technology used and the big uncertainty, so neglecting the risk

management will result in a lot of problems.

The following pages will focus on representing an overall view of risk management processes,

factors affecting the success of application and a case study from a real project. The case study

will include risk identification and risk qualitative assessment.

2. Literature Review

The literature review of this paper include two main topics: (1) The construction of tunnels by

TBM method, (2) Risk management and success factors.

2.1 The Construction of Tunnels by TBM Method

Tunnels are artificial underground passage that constructed for many purposes such as: highway, rail

way, sewerage, water supply and pedestrian. "There are some techniques to construct a tunnel, as

the following.

Cut and Cover System.

Pipe Jacking System (Micro Tunneling).

Shield Tunneling (TBM).

New Austrian Tunneling Method (NATM).

Immersed-Tube Tunneling System "[1].

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The choice of tunnelling method will be dictated by geological and hydrological conditions,

available resources, uses of the ground surface, cross section dimension, Environmental impact

limitations and other factors.

One of the common construction method of tunnels is tunnel boring machine method " TBM", and that is because it`s has many advantage enough to be selected to most of tunnelling projects around the world. "The advantages are such as fast construction, more safety, decrease the construction cost, decrease the number of temporary structure needed " [2]. " The sequence of work can be summarized as the following steps: The TBM moved forward as it

excavated the tunnel by extending the pushing jacks at the back. When the advancement of the

machine reached distance of the length of a ring, the excavation stopped and the pushing jacks

were retrieved, a concert circular ring in form of a numbers of segments were then put together

at the tail of the shield. The pushing arms were once again extended in full contact with the

concert ring just erected and excavation resumed. The cycle of excavation and ring erection

repeated as the TBM advanced to form the lining of the tunnel"[3].

2.2 Risk Management and Success Factors

Risk management includes a group of processes which will be clarified at next pages, also each

process has to regard some factors to ensure the best result. According to PMBOK ® Guide –

Fifth Edition, Risk management has six processes are as follows:

• "Plan Risk Management. • Identify Risks. • Perform Qualitative Risk Analysis. • Perform Quantitative Risk Analysis. • Plan Risk Responses. • Monitor and Control Risks"[4].

These processes are not separated, but they are integrated to themselves and to whole project.

Also all stakeholder has to participate at the different processes.

2.2.1 Introduction to Risk Management

"The definition of Project Risk Management, as defined in the PMBOK ® Guide – Fifth Edition, is

the basis for this practice standard: Project Risk Management includes the processes concerned

with conducting risk management planning, identification, analysis, responses, and monitoring

and control on a project. The PMBOK ® Guide – Fifth Edition also states: The objectives of

Project Risk Management are to increase the probability and impact of positive events, and

decrease the probability and impact of negative events in the project. In the PMBOK ® Guide –

Fifth Edition, project risk is an uncertain event or condition that, if it occurs, has a positive or

negative effect on a project’s objectives.” Project objectives include scope, schedule, cost, and

quality" [4].

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All the time we have risks in our life generally. Most of people think that risks are bad things

which will destroy the project or at less will cause a bad effect, but that’s not true at more. Risk

may be a threat or an opportunity so it may bring good events in addition to bad events. In brief

we can say that risk is like cost, scope and quality, so if manage it well, there will be no problem.

For any project, risk management is the responsibility of the project manager and project team

members. Risk management is must start early at the project planning phase and go through

execution and closure phases. It must be iterative and integrated to the other project

management areas.

2.2.2 Plan Risk Management

Plan risk management is the first step that being done early the planning phase. It`s identify the

scope of risk management. During this process, we determine the activities required to manage

the risks, relations between activities, resources needed, roles, responsibility and risk

management policy.

Plan risk management is a progressive elaborated and there are also some factors must be considered to ensure the success of this process - as per practice standard for project risk management, By PMI- as follows:

- "Identify and Address Barriers to Successful Project Risk Management. - Involve Project Stakeholders in Project Risk Management. - Comply with the Organization’s Objectives, Policies, and Practices"[5].

2.2.3 Identify Risks

Identify risks is a process done during the planning phase and still active along the project.

Identify risk process is very critical process because any unidentified risk will not be included

during the successor processes which may lead to big problems. During this process we identify

all probable risks as possible. By using tools and techniques in order to discover all possible risks

that may face the project, but actually some risks will be un-discovered so the process of risk

identification must be iterative along the project life. The identified risks must be written simply

in risk register and must provide the details required to be understood well. There are also some

factors must be considered to ensure the success of this process - as per practice standard for

project risk management, By PMI- as follows:

- "Early Identification.

- Iterative Identification.

- Emergent Identification.

- Comprehensive Identification.

- Explicit Identification of Opportunities.

- Multiple Perspectives.

- Risks Linked to Project Objectives.

- Complete Risk Statement.

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- Ownership and Level of Detail"[5].

2.2.4 Perform Qualitative Risk Analysis

Perform Qualitative Risk Analysis is a process done during the planning phase and when a new

risk has been discovered we recall qualitative risk analysis to rank it. Perform qualitative risk

analysis is the first step of analyzing and assessing the discovered risk during the risk

identification process. This process must be accurate, rapid, cost effective and based on agreed-

upon characteristics. In this process, all risks are ranked according to their probabilities and

impacts so the data of the risk must be accurate as possible. There are two important outputs

will be resulted by the end of this process. The first output is updating the risk register which

contain all important and high level information about the risks which have a medium and high

ranking. The second output is the watch list that includes the low rank risks. There are also some



- "Use Agreed-Upon Approach.

- Use Agreed-Upon Definitions of Risk Terms.

- Collect High-Quality Information about Risks.

- Perform Iterative Qualitative Risk Analysis"[5].

2.2.5 Perform Quantitative Risk Analysis

Perform quantitative risk analysis is the second step of risk assessment that numerically assess

risks. Sometime this step may be skipped for some reasons such as the project is too small,

there are no enough data or the cost of doing quantitative analysis is more than the cost saved

by doing it. We make the decision of doing it or not during planning risk management process.

By the end of this process we determine the probability of achieving the objective of the

projects. Also the contingency required for time or cost can be determined at this process.

There are differences between qualitative risk analysis and quantitative risk analysis could be

summarized as: qualitative analysis is a subjective process and the quantitative analysis is an

objective process. There are also some factors must be considered to ensure the success of this

process - as per practice standard for project risk management, By PMI- as follows:

- "Appropriate Project Model.

- Commitment to Collecting High-Quality Risk Data.

- Unbiased Data.

- Overall Project Risk Derived from Individual Risks.

- Interrelationships Between Risks in Quantitative Risk Analysis"[5].

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2.2.6 Plan Risk Responses

Plan risk response comes after finishing risk analysis and regards the outputs from the previous

processes. The risk response is a group of actions to handle risk. So each identified risk will have

a response and a someone or an organization is assigned to do the actions at the right time and

in a right sequence. When we plan a response for a risk, it may result in a secondary risk that

also should be handled with a suitable response. Although all risks are planned to have response

actions, but during execution we may face risks that did not identified early so it handled by

work around response and then we have to review the risk register to add any probable risks.

The response plan assigned to negative risks may be transfer, avoid, accept or mitigate. The

response plan assigned to positive risks may be share, enhance, accept, exploit. Any selected

strategy must be approved by the stakeholder and clearly communicated. There are also some



- "Clearly Define Risk-Related Roles and Responsibilities.

- Communicate.

- Specify Timing of Risk Responses.

- Provide Resources, Budget, and Schedule for Responses.

- Address the Interaction of Risks and Responses.

- Ensure Appropriate, Timely, Effective, and Agreed-Upon Responses.

- Address Both Threats and Opportunities.

- Develop Strategies before Tactical Responses"[5].

2.2.7 Monitor and Control Risks

Planning without monitoring and controlling is a wasted effort, so planning must be followed by

monitor and control during the execution phase. Monitor and control is very essential and

contributes to risk management. In the real world, there is no perfect plan so any plan must be

continuously adjusted regarding the actual data. During this process we are monitoring risk

trigger, implementing the response action to occurred risks, discovering new risks and adjusting

risks response if needed. There are also some factors must be considered to ensure the success

of this process - as per practice standard for project risk management, By PMI - as follows:

- "Integrate Risk Monitoring and Control with Project Monitoring and Control.

- Continuously Monitor Risk Trigger Conditions.

- Maintain Risk Awareness"[5].

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3. A Case Study The coming pages introduce a risk management case study for a real project in Egypt.

The project is a tunneling project and "TBM" is the used method for the tunnel

excavation. Some of data will be hidden due to privacy conditions.

3.1 Establishing the Context

Project name: Cairo Metro, Line No (3), Phase (2).

Project Tender Type: The tender is "Selective Tender"

Type of Contract: The Contract used is "Unit Price"

Total Price of Civil Works: **

Project units: A group of tunnel lines linked together with stations.

Method of construction: - For tunnels: TBM method was used.

- For station: Top-down construction method was used and the diaphragm wall was used

as soil supporter.

Project objective: - Safe and stable structures.

- Provide a sheep, easy and helpful transportation mean.

Project location: Cairo-Egypt.

Stakeholders identification and analysis: Stakeholders: 1. The National Authority for Tunnels. 2. Siesta Egypt company. 3. Arab contractors company. 4. Orascom company. 5. Vinci company. 6. Bouygues company. 7. The project members and all working stuff. 8. The sub-contractors. 9. The suppliers. 10. The Environment. 11. The community. 12. The neighbors and all the affected people due to construction. 13. The Media. 14. Transportation and traffic ministry.

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Stakeholder analysis:

name Stakeholder Key issues and objectives

The National Authority for Tunnels

Delivered on time, receiving the project with agreed quality, helping in solve the problems. No additional costs.

Siestra Egypt company

To maximize the profit and minimize the cost. Obtain a good brand in Egypt. To be selected for another projects in the Egyptian market.

Arab contractors company

To maximize the profit and minimize the cost.

Orascom company


Vinci company

To maximize the profit and minimize the cost. Obtain a good brand in Egypt. To be selected for another projects in the Egyptian market.

Bouygues company

To maximize the profit and minimize the cost. To be selected for another projects in the Egyptian market.

The project members and all working stuff

Get a good experience and better position and get a good paid.

The sub-contractors


The Environment

To ensure that construction processes are not pollute the environment over allowable limits.

The community

To obtain a metro line represented an easy transportation mean.

The neighbors and all the affected people due to construction

To have a good effect and not affect their buildings stability.

The Media

To reflecting the real images of the work progress of the project to the community.

The suppliers To maximize the profit and obtain a good brand.

Transportation and traffic ministry

A project helps transportation and traffic in Cairo. Participate in operate the project at the future.

Stakeholder analysis (Table – 1)

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3.2 Risk Identification

Tools and technique used in the process: Historical Review- Brainstorming- SWOT analysis-

Interviewing- Delphi technique- Expert judgment.

Risk categories are Safety, Construction, Management, Economic, Political and Communistically.

The percentage of each category being shown at the following chart (1):

The resulted risk list as follows:

No Risk name Risk Category Risk Description

1 Failure of tower cranes Safety

There are many causes of failure as following: bad design of footing-water seepage under footing- over loading-wind velocity bigger than the allowable.

2 TBM equipment sink in the soil.

Construction Due to TBM weight and at the case of soft soil.

Safety10%

Construction38%Management

42%

Politiacal and Communistically

6%

Economic4%

Risk Categories % - Chart (1)

Safety

Construction

Management

Politiacal and Communistically

Economic

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3 Approval and permits. Management

It`s probable that an entity likes the regulators or governmental authorities Object to an activity and stop work. Also permits usually take a long time.

4 Poor sub-contractor performance.

Management Sub-contractor may deliver work after it`s deadline or less than the quality level required.

5 Lack of Oxygen underground.

Safety Underground there is not enough Oxygen.

6 Noise and air pollution Political and

Communistically

Due to excavation, concreting, and equipment's there might be noise and air pollution.

7 Curing of concrete surrounding with soil form all direction.

Construction Diaphragm wall is surrounding with soil from all direction

8 Casting concrete for deep section (about40m).

Construction Deep section causes many problems like Segregation

9 Unpredictable existence of a soil type.

Construction

Unpredictable soil might causes more time and more cost, on the other hand may causes less time and cost.

10 Rings delay of delivering. Management

Tunnel section contains from no of rings =8, this mean any delay of rings delay the work ( delay critical activity)

11 Equipment's breakdown Management Breakdowns delay work

12 Injures at the site Safety

Injures increase absence, complaints and hidden cost

Decrease production rate

Provide labours with a bad morals

13 Stopped the traffic. Political and

Communistically

The stations sites are located in a location which may a random neighbourhood, traffic and housing area may be exist.

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14 Delaying of the ready mix concrete.

Management Delay the concrete means always delays a critical activity.

15 Site safety system. Safety A big project likes tunnels project has big number of safety risks.

16 Lack of labour skills. Management

A tunnel project is a complex project in addition to the number of tunnel project in Egypt is not big, therefore a lack of skilled labours.

17 Languages Varity. Management

As the project involved in a big number of companies and there are foreigners so there are more than language may make understanding others is difficult.

18 Pipes and cables posed the tunnels way or station

Construction Pipes and cables posed the tunnels way or station will delay the work, causes additional cost and problems.

19 Change orders. Management Any changes may be exist along project duration.

20 Approval / Rejection of the inspection from the consultant.

Construction

Prior any implementation of the works, it preliminary to acquire the related permits from the governmental authorities.

21 Estimation errors. Management Estimation of time or cost may contain errors that affect the project scope seriously.

22 Cope with the new technologies.

Management Some of the project items used new technology in execution processes.

23 In-time materials not being delivered.

Management In-time materials not being delivered will delay work.

24 Penalties due to delays. Management Delivering items after their delivery times resulted in penalties.

25 Concerting at a bad weather.

Construction Concreting at rainy weather or hot weather causes problems.

26 Excavation at a bad weather.

Construction Rainy weather increases soil volume, on the other hand windy weather pollutes air.

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27 unclear understanding of design sheets.

Construction Some of details may be un clear or

28 Discounts Management Buy a large number of something such as caravans and silos often followed by a discount.

29 Co-ordination problems. Management Due to the big number of contractors at the site. Co-ordination problems are probable.

30 Bad injection. Construction

Soil injection is so important work and sensitive, therefore any problem an injection process will cause problems during excavation.

31 Storage strategy. Management

A lot of Material in the site need good strategy for storage like (Reinforcement, bentonite Shuttering).

32 Bad lining from TBM. Construction

TBM lines the tunnel section and if there are any defects in lining, it will cause ground water seepage to the tunnel.

33 High employees turn over(resign).

Management

The market became very competitive for better opportunities of other vacancies at different construction projects.

34 Inflation impact on cash flow.

Economic The prices are subject to increases affecting the cash out.

35 Tilting of diaphragm wall.

Construction Diaphragm wall must be vertical

36 Bad bentonite mix. Construction If bentonite properties are not satisfying specifications, the mix will not act As It Should Be.

37 Bad insulation (not satisfy specifications).

Construction Bad insulations means a water seepage which a big problem

38 Ground settlement. Construction

Because of deep excavation for tunnel or stations, it is probable that settlement occurs which certainly will affect near building negatively.

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39 Errors due to a variety of steel types delivered to the project.

Management

A variety types of steel are delivered daily to the sites, the problem is representing in use a type instead of the targeted type.

40 Delay penalties applied for the contractor.

Management The owner needs to be delivered on the planned time.

41 Dewatering for station works.

Construction

Dewatering is so important work and sensitive, therefore any problem an injection process will cause problems during excavation.

42 Providing car parking. Political and

Communistically The engineers and workers need a car parking area.

43 Windy weather. Construction

Windy weather stopped operating the TC as a safety role and pollutes the air with the volunteers soil particles due to excavation and transportation.

44 Shuttering defects. Construction Shuttering affects concrete quality directly

45 Excavation injures. Safety Excavation is considered as one of the most danger activities in construction projects.

46 Lacks of petroleum materials are needed.

Economic Nowadays events in Egypt are threatening to continuous Lacks of petroleum materials.

47 Strikes Management After 25 January resigns become a risk for al projects.

48 new governments Political and

Communistically A new government comes may cancel the project.

49 Design problems. Management Design may not be adapted to construction.

Risk list (Table – 2)

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3.3 Qualitative Risk analysis

During this process all risks were analyzed according to their probability and impact. The

range of probability and impact is within (0 – 100) %.

The assessment of impact and probability was done by the project team and external

experts.

According to "Risk management for overseas construction projects, He Zhi, School of

Civil and Structural Engineering, Nanyang Technological University, Singapore 2263- page

234 "[6].

R=P×I (Equation – 1)

Where:

"R" is the degree of risk, within [0,100] %.

"P" is the probability of the risk occurring, within [0,100] %.

"I" is the degree of impact of the risk, which is defined as being within [0,100] %.

The following chart is showing the ranking of risks in a simple view. The chart shows a

variety of ranks as risks may be high risk, medium, or low.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Ran

kin

g

Risks

Risks Ranking - chart (2)

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4. Conclusion

All projects should be risk managed to catch their objectives. Risk management is not limited to

planning phase only, but also must go through execution phase. There are some factors must be

considered during risk management process in order to implement a successful process. Tunnels

construction are complex and risky projects includes a big number of risks that must be

managed. When you manage risks, you provide a great support to your project and organization

as follows:

- Savings excessive costs

- Protect the project period

- Improve the performance

- Obtain a great data base and lessons learned

- Improve future estimate

- Support the brand of your organization

- Drive your organization forward

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Bibliography

No. Description

1. Tunnel construction lectures

Dr. Ahmed Abdel-Atty Gab-Allah

Zagazig University

2. The Advantages Of Tunnel Boring : A Qualitative/Quantitative Comparison Of D&B And TBM Excavation

Peter J Tarkoy, PhD, Geotechnical and Tunnel Construction Consultant and James E Byram, PhD, Senior Research Scientist

3. Engineering Survey System for TBM (Tunnel Boring Machine) Tunnel Construction

Andrew Hung Shing Lee, Hong Kong

4. PMBOK ® Guide – Fifth Edition

Project Management Institute

5. Practice Standard For Project Risk Management

Project Management Institute

6 Risk Management For Overseas Construction Projects

He Zhi

School of Civil and Structural Engineering, Nanyang Technological University, Singapore 2263

the major risks in tbm bored tunnels projects

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